import java.util.Scanner;

/**
 * @author ghp
 * @title
 * @description
 */
public class Test {

    // 精度控制，精度控制在小数点后六位
    public static final double EPS = 1e-6;

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double n = sc.nextDouble();
        double res = sqrt(n);
        System.out.printf("%.2f", res);
    }

    public static double sqrt(double n) {
        double l = 0, r = n;
        while (l + EPS < r) {
            double mid = (r-l)/2 + l;
            if (mid * mid >= n) {
                r = mid;
            } else {
                l = mid;
            }
        }
        return r;
    }
}
